Adaptation of instrument cluster gauges for twist-lock mounting

ABSTRACT

A gauge assembly is provided including a terminal carrier including a base portion, a head portion extending from a first side of the base portion, and a plurality of legs extending from a second side of the base portion. The head portion includes a twist lock locking element disposed on a side thereof. A bobbin and coil assembly is supported by the terminal carrier. The bobbin and coil assembly rotatably supports a spindle and magnet. A plurality of electrical terminals extend through the base portion of the terminal carrier and terminate at one end into a bent contact portion adjacent to the head portion which engage electrical contact pads disposed on the printed circuit board. The electrical terminals have a second end electrically connected to a coil of the bobbin and coil assembly. A plurality of mounting bosses are mounted to the display panel and are provided with sloped surfaces for guiding the gauge assembly to a centered position when the display panel and printed circuit board are mounted together. One of the mounting bosses is attached to the printed circuit board.

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION

The present invention relates generally to a gauge assembly for use in avehicle instrument cluster, and more particularly, to a gauge assemblywith a twist lock mounting feature.

BACKGROUND AND SUMMARY OF THE INVENTION

Instrument cluster gauges, such as speedometers, tachometers, fuel andtemperature gauges used in modern vehicles commonly include a pointerbody or needle coupled to a permanent magnet. The magnet is generallycarried in a plastic housing or bobbin, which is wrapped with wirecoils. During operation of the vehicle, current flowing through thecoils creates a magnetic field, and the magnet rotates within thehousing to align itself in force balance relationship with the magneticfield. Since the pointer body rotates with the magnet, positioning ofthe pointer body is controlled by the direction and magnitude of thecurrent in the coils. To provide for steady movement of the pointerbody, a viscous fluid is carried in the housing to damp the rotationalmovement of the magnet.

Current gauge assembly designs include a plurality of post-liketerminals which are inserted in gauge mounting clips which are providedon the circuit boards. The gauge assembly is typically mounted to thedisplay panel using mounting screws. Typical gauges are disclosed inU.S. Pat. Nos. 5,219,135 and 5,631,419. A disadvantage of these types ofgauges is that they require mounting screws to mount the gauges to thedisplay panel, and thus require a considerable amount of labor formounting the gauge to the instrument cluster assembly. In addition, theelectrical contact through the terminal posts and the gauge clips cancreate problems due to intermittent contact.

Accordingly, it is an object of the present invention to provide analternative mounting technique for mounting a gauge to an instrumentcluster assembly. These and other objects of the present invention areobtained by providing a gauge assembly including a terminal carrierincluding a base portion, a head portion extending from a first side ofthe base portion, and a plurality of legs extending from a second sideof the base portion. The head portion includes a pair of twist locklocking elements disposed on the side thereof. A bobbin and coilassembly is supported by the terminal carrier. The bobbin and coilassembly rotatably supports a spindle and magnet. A plurality ofelectrical terminals extend through the base portion of the terminalcarrier and terminate at one end into a bent contact portion adjacent tothe head portion. The bent contact portions engage electrical contactpads disposed on the printed circuit board. The electrical terminalshave a second end electrically connected to a coil of the bobbin andcoil assembly. A plurality of mounting bosses are provided on the backof the display panel to receive and guide the gauge assembly to itsproper location.

The gauge assembly of the present invention eliminates the need forgauge mounting clips on the circuit board, reduces problems due tointermittent contact through the gauge clips and provides a higher levelof reliability with the twist/wipe contacts used in the presentinvention. Furthermore, the gauge assembly of the present inventioneliminates mounting screws and the associated assembly labor. The gaugeassembly design of the present invention also reduces the package heightof the gauge assembly which in turn reduces the overall thickness of theinstrument cluster.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood however that the detailed description and specificexamples, while indicating preferred embodiments of the invention, areintended for purposes of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a perspective view of an instrument cluster assembly accordingto the principles of the present invention;

FIG. 2 is a partial cross-sectional view of a gauge assembly accordingto the principles of the present invention;

FIG. 3 is a side view of the gauge assembly of the present inventionhaving positioning bosses mounted to the display panel for guiding thegauge assembly to its final position;

FIG. 4 is a perspective view of the terminal carrier of the gaugeassembly according to the principles of the present invention;

FIG. 5 is a side view of the gauge assembly of the present inventionwith the housing cut away and illustrating the long locking elementdisposed on one side of the terminal carrier;

FIG. 6 is a side view of the terminal carrier illustrating the shortloading element disposed on an opposite side of the terminal carrier;

FIG. 7 is a partial view of a printed circuit board having a keyedopening for receiving the twist-lock gauge assembly of the presentinvention, and illustrating the electrical contact pads for engaging theelectrical terminals of the gauge assembly;

FIG. 8 illustrates the engagement of the twist-lock locking elements ofthe gauge assembly according to the principles of the present invention;

FIG. 9 is a bottom view of the gauge assembly according to theprinciples of the present invention;

FIG. 10 is an exploded perspective view of the gauge assembly accordingto the principles of the present invention;

FIG. 11 is a cross-sectional view taken along line 11--11 of FIG. 2;

FIG. 12 is an exploded perspective view of the bobbin assembly accordingto the principles of the present invention; and

FIG. 13 is a perspective view illustrating the mounting bosses forguiding the gauge assembly of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the accompanying figures, the twist-lock gaugeassembly of the present invention will now be described. FIG. 1illustrates an instrument cluster 10 including a display panel 12 andprinted circuit board 14. The printed circuit board 14 includes aplurality of circuit elements which are standard for many instrumentcluster printed circuit boards. A plurality of light bulbs 16 aremounted to the printed circuit board for providing light to the displaypanel 12 using known illumination techniques. A plurality of gaugeassemblies 20 according to the principles of the present invention aremounted to the printed circuit board 14 in a manner that will bedescribed herein.

The gauge assembly 20 will now be described with reference to FIGS.2-13. The gauge assembly 20 includes a terminal carrier 22 best shown inFIGS. 4-6. The terminal carrier 22 includes a base portion 24, a headportion 26 extending from one side of the base portion 24 and aplurality of legs 28 extending from an opposite side of the base portion24. The head portion 26 includes a pair of twist-lock locking elements30, 32. One locking element 30 is a long locking element while thesecond locking element 32 is a short locking element. A plurality ofelectrical terminals 34 extend through openings 36 provided in the baseportion 24 of the terminal carrier 22. The electrical terminals 34terminate at a first end into a bent contact portion (or twist/wipecontacts) 38 adjacent to the head portion 26 of the terminal carrier 22.Terminals 34 each extend along a leg 28 of the terminal carrier. Legs 28are provided with recessed grooves 40 for receiving the terminals 34therein, as best shown in FIG. 11. The gauge assembly 20 also includes agenerally cup-shaped housing 42 which is provided with a base portion 44having a plurality of holes 45 for receiving the legs 28 of terminalcarrier 22. The legs 28 are provided with outwardly extending feetportions 46 which engage the distal end of the sidewall portion of thehousing 42. In addition, housing 42 is provided with clinch tabs 50which are received in a slot 52 in the base portion 24 of terminalcarrier 22. Clinch tabs 50, after being inserted in slots 52, are bentover in order to secure the housing 42 to the terminal carrier 22.

A coil and bobbin assembly 54 is supported by the legs 28 of theterminal carrier 22. The coil and bobbin assembly 54 includes atwo-piece bobbin assembly 56 best shown in FIG. 12. The bobbin assembly56 includes a first housing element 58 and a second housing element 60.The first housing element defines an annular wall portion 62 having anouter mating surface 64. A generally planar end wall portion 66 isprovided with an opening 68. A plurality of axially extending armportions 70 are provided with axially extending channels 72 which areadapted to receive the legs 28 of the terminal carrier 22. Similarly,the second housing element 60 is provided with an annular wall portion74 which has an interior engagement surface. A generally planar end wall76 is provided with an axially extending nose portion 78 with an opening80 extending therethrough. The annular wall portion 62 of first housingelement 58 is received within the annular wall portion 74 of secondhousing element 60 in order to define a generally cylindrical sealedchamber 82, as best shown in FIG. 2. A disk-shaped magnet 84 issupported within the chamber 82 by a spindle 86 which has a first endwhich extends into opening 68 of first housing element 58, and a secondend which extends through bore 80 and the nose portion 78 of secondhousing element 60. The second housing element 60 is also provided witha plurality of arms 88 which are provided with axially extendingchannels 90 which receive the legs 28 of terminal carrier 22, as bestshown in FIG. 11. The bobbin assembly 56 is provided with four wrappedcoils 92 as shown in FIG. 9, and as is known in the art.

The bobbin and coil assembly 54 is slidably received on the legs 28 ofterminal carrier 22. The upper end of the arms 70 abut against ashoulder portion 94 o f the legs 28. A retaining ring 96 is insertedbelow the bobbin and coil assembly 54 and engages the end of the legs 88of second bobbin housing element and retains the bobbin and coilassembly 54 in place. The retaining ring 96 is held in place by aplurality of internal projections 98 provided on the interior surface oflegs 28. The electric terminals 34 are bent inward at a second endthereof as shown in FIG. 2 and individually connected one of the coils92 by solder or welding.

The gauge assembly 20 of the present invention is mounted to a printedcircuit board 14. The printed circuit board is provided with an opening102 defining a pair of arcuate shaped edges 104 circularly symmetricabout a center, and pair of aperture wing boundary portions 106, 108.The wing boundary portion 106 has a larger dimension than the wingboundary portion 108. A plurality of electric conducting pads 110 areprovided around the periphery of the opening 102 at spaced positions.During assembly, the head portion 26 of the gauge assembly 20 isinserted through opening 102 so that the short locking element 32extends through shorter wing boundary portion 108 and the long lockingelement 30 extends through longer wing boundary portion 106. The gaugeassembly 20 is then rotated as illustrated in FIG. 8 so that lockingelements 30 and 32 lockingly engage the printed circuit board 14.Furthermore, during the locking engagement, the bent contact portions 38of terminals 34 each engage an electrical contact pad 110 for providingelectrical communication to the terminals 34. After each of the gaugeassemblies 20 are mounted to the printed circuit board 14 as well as anyother accessories, the printed circuit board 14 and display panel 12 areassembled to one another.

The display panel 12 is provided with a plurality of mounting bosses 116which are provided with a sloped guide surface 118 which engage thehousing 42 of the gauge assemblies 20 and guide them to the generallyflat platform portion 120 of the mounting bosses 116, thereby properlyguiding the spindle 86 through the opening 122 in the display panel 12.One of the mounting bosses 116' has a height which is designed toproperly space the display panel 12 from the printed circuit board 14.The mounting boss 116' is provided with a threaded opening 124 at anupper end thereof for threadedly receiving a screw 126 which is insertedthrough an opening 128 in the printed circuit board 14. Thus, the screw126 secures the printed circuit board 14 to the display panel 12 at aproper spaced location. A pointer 130 is then assembled on the spindle86 in order to complete the assembly of the instrument cluster 10.

The long locking element 30 and short locking element 32 are provided sothat the gauge assembly 20 can only be assembled in one orientation sothat the proper electric contact pads 110 engage the proper terminals 34for controlling the gauge assembly 20. Current flowing through the coils92 creates a magnetic field, and the magnet 84 rotates within the bobbinassembly 56 to align itself in forced balanced relationship with thefield. Since the spindle 86 rotates with the magnet 84, positioning ofthe pointer body 113 is controlled by the magnitude of the current inthe coils 92. To provide for steady movement of the pointer body 113, aviscous fluid is carried in the magnet chamber 82 to damp the rotationalmovement of the magnet 84. With the gauge assembly 20 of the presentinvention, the twist lock mounting eliminates the necessity of thescrews and the accompanying labor which are required with previousdesigns. Furthermore, the elimination of the terminal posts which arealso used in previous designs, allows the reduction and overallthickness of the instrument cluster and allows the elimination of thegauge mounting clips on the circuit board. Furthermore, the twist-wipecontacts 38 used in the design of the present invention have higherreliability than the intermittent contact problems which occur with thegauge clips.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

What is claimed is:
 1. A display panel assembly, comprising:a displaypanel; a printed circuit board disposed behind said display panel; agauge assembly mounted to said printed circuit board, said gaugeassembly including a housing and a bobbin and coil assembly supportedwithin said housing, said bobbin and coil assembly rotatably supportinga spindle and magnet, said spindle extending through an opening in saiddisplay panel and having a pointer mounted on an end thereof; whereinsaid display panel includes a plurality of mounting bosses mounted tosaid display panel surrounding said opening in said display panel, saidmounting bosses having a sloped guide surface contacting, said gaugeassembly relative to the opening in said display panel.
 2. The displaypanel assembly according to claim 1, wherein one of said plurality ofmounting bosses are connected to said printed circuit board by afastener.
 3. A display panel assembly, comprising:a display panel; aprinted circuit board disposed behind said display panel; a gaugeassembly mounted to said printed circuit board, said gauge assemblyincluding a housing and a bobbin and coil assembly supported within saidhousing, said bobbin and coil assembly rotatably supporting a spindleand magnet, said spindle extending through an opening in said displaypanel and having a pointer mounted on an end thereof; wherein saiddisplay panel includes a plurality of mounting bosses mounted to saiddisplay panel surrounding said opening in said display panel, at leastone of said plurality of mounting bosses contacting and spacing saiddisplay panel from said printed circuit board.
 4. The display panelassembly according to claim 3, wherein one of said plurality of mountingbosses are connected to said printed circuit board by a fastener.
 5. Adisplay panel assembly, comprising:a display panel; a printed circuitboard disposed behind said display panel; a gauge assembly mounted tosaid printed circuit board, said gauge assembly including a housing anda bobbin and coil assembly supported within said housing, said bobbinand coil assembly rotatably supporting a spindle and magnet, saidspindle extending through an opening in said display panel and having apointer mounted on an end thereof; wherein said display panel includes aplurality of mounting bosses mounted to said display panel surroundingsaid oppose in said display panel, said mounting bosses having asubstantially flat platform which contacts and guides.
 6. The displaypanel assembly according to claim 5, wherein one of said plurality ofmounting bosses are connected to said printed circuit board by afastener.